This competing renewal application seeks support to continue a longstanding program of research on stimulus control development in individuals whose intellectual disabilities render them difficult-to-teach with the pedagological techniques of typical educational environments. The program has two major objectives: (1) to further understanding of basic stimulus control processes in learning and (2) to apply the resulting knowledge to improve our ability to teach and evaluate individuals with disabilities. Past research under NICHD sponsorship has allowed us to develop numerous beneficial intervention approaches that have been documented in our past publications and are now being applied effectively in intervention settings. We intend this new program to continue that tradition, and to extend it into several new and/or substantially expanded areas, including: (a) formalized studies of the interaction of participant diagnostic status (autism, Down Syndrome, undifferentiated mental retardation, etc.) with environmental contingencies;(b) increased emphases on sensory and perceptual processes involved in detecting stimulus relations within displays that include both visual and auditory stimuli;and (c) expanded use of methodologies that reveal behavioral and biobehavioral processes that typically go unmeasured in research of this type. Four projects are proposed: Projects 1 and 2 will study stimulus structure variables that are important in promoting desirable forms of stimulus control in functional academics and augmentative/alternative communication, respectively. Project 3 will study stimulus control processes in the detection of facial expression and emotion by persons from various disability groups. Project 4 will take the program into a new area, concentrating on processes involved in the development of stimulus control by auditory stimuli. These projects are united by a common interest in merging methods and perspectives of several subdisciplines of behavioral/behavioral sciences (behavior analysis, cognitive neuroscience, and developmental psycholinguistics) in research that can be effectively translated to the classroom and clinic. The project's theoretical orientation is explicitly transdisciplinary, with contingency detection and learning as a central organizing concept. The projects are united also by two core units that provide essential cross-project services. The Program Administration and Project Coordination Core (A) will oversee and coordinate program operations. The Shared Instrument Core (B) promotes effective use of shared equipment and facilities. Both core units also are tasked with effectively interfacing with the UMMS MRDDRC, which serves as a further source of project support and integration.